阅读说明：本技术 固井二界面胶结质量评价装置及方法 (Cementing quality evaluation device and method for well cementation two-interface ) 是由 郭小阳 贾禛 李永刚 胡开利 毛德森 罗亮 江洪 于 2019-10-29 设计创作，主要内容包括：本发明涉及固井二界面胶结质量评价装置及方法。该装置由圆柱形釜体1、岩心4、流体加压泵11、压力传感器12等组成,釜体有可拆卸的上密封盖2、下密封盖3,上密封盖有进液进气口6、泄压阀9和压力传感器12,下密封盖有出液出气口7；釜体内有岩心4,岩心表面有滤饼,岩心与釜体之间的环形空间内有水泥环。该方法包括：将带有滤饼的岩心抽真空,使岩心饱和树脂；将岩心放入釜体中,加入固井水泥浆,养护一定时间,岩心与釜体内壁之间形成水泥环；向釜体内注入流体；记录二界面滤饼发生破坏形成流体窜通通道时的破裂压力,得到二界面胶结系数。本发明能有效避免流体从岩心渗流,真实反映固井二界面的胶结质量,具有广阔的市场前景。(The invention relates to a cementing quality evaluation device and method for a well cementation two-interface. The device comprises a cylindrical kettle body 1, a rock core 4, a fluid pressure pump 11, a pressure sensor 12 and the like, wherein the kettle body is provided with an upper sealing cover 2 and a lower sealing cover 3 which are detachable, the upper sealing cover is provided with a liquid inlet 6, a pressure release valve 9 and the pressure sensor 12, and the lower sealing cover is provided with a liquid outlet 7; a rock core 4 is arranged in the kettle body, a filter cake is arranged on the surface of the rock core, and a cement sheath is arranged in an annular space between the rock core and the kettle body. The method comprises the following steps: vacuumizing the rock core with the filter cake to saturate the rock core with resin; putting the core into a kettle body, adding well cementing cement slurry, and maintaining for a certain time to form a cement sheath between the core and the inner wall of the kettle body; injecting fluid into the kettle body; and recording the fracture pressure when the filter cake on the two interfaces is broken to form a fluid channeling channel, and obtaining the cementation coefficient of the two interfaces. The invention can effectively avoid the seepage of fluid from the rock core, truly reflects the cementing quality of the well cementation two interfaces and has wide market prospect.)

1. the cementing quality evaluation device for the well cementation two-interface is composed of a cylindrical kettle body (1), a rock core (4), a heating sleeve (5), a heat insulation sleeve (8), a fluid pressure pump (11), a pressure sensor (12) and a pressure recorder (13), and is characterized in that the inner diameter of the kettle body (1) from the top to the bottom is gradually reduced, the inner wall of the kettle body forms an inverted circular truncated cone shape, and the kettle body is provided with a detachable upper sealing cover (2) and a detachable lower sealing cover (3); the upper sealing cover is provided with a liquid inlet (6), a pressure release valve (9) and a pressure sensor (12), the liquid inlet is connected with a fluid pressure pump (11) through a one-way valve (10) and a pipeline, and the pressure sensor is connected with a pressure recorder (13); the lower sealing cover is provided with a liquid outlet (7); a rock core (4) is arranged in the kettle body, the rock core is placed on the inner surface of the lower sealing cover, a filter cake is arranged on the surface of the rock core, and a cement sheath is arranged in an annular space between the rock core and the kettle body; the kettle body is externally provided with a heating jacket (5) and a heat-insulating jacket (8).

2. The device for evaluating the cementing quality of the well cementation two interfaces of claim 1, wherein the inner wall of the top of the kettle body and the outer wall of the top of the kettle body form an included angle of 7 degrees to 8 degrees.

3. The device for evaluating the cementing quality of the well cementation two interfaces of claim 1, wherein at least two liquid outlet air outlets are arranged and are uniformly distributed between the rock core and the inner wall of the kettle body.

4. A method for evaluating the cementing quality of a cementing interface by using the device of claim 1, 2 or 3, comprising the following steps in sequence:

(1) placing the rock core in a filter cake pressing device to form a compact drilling fluid filter cake on the surface of the rock core;

(2) placing the rock core with the filter cake in a vacuum tank, and dripping resin into the rock core while vacuumizing to saturate the rock core with resin, wherein the resin is coagulated together with cement slurry without affecting the structure of the filter cake;

(3) placing the core into a kettle body, adding well cementation cement slurry into an annular space between the core and the kettle body, and maintaining under the experimental requirement condition to form a cement sheath between the core and the inner wall of the kettle body;

(4) a fluid pressurizing pump injects fluid into the kettle body through a one-way valve and a liquid inlet, when the pressure is raised to a certain value, the fluid penetrates through two interfaces where filter cakes exist, a fluid channeling channel is formed on the two interfaces, and the fluid is discharged through a liquid outlet and a gas outlet;

(5) recording the fracture pressure when the filter cake of the second interface is damaged to form a fluid channeling channel to obtain a cementation coefficient of the second interface, thereby evaluating the cementation quality of the second interface, wherein the calculation formula of the cementation coefficient of the second interface is as follows:

in the formula, gamma is a two-interface cementation coefficient and is dimensionless;

r₁is the outer diameter of the core containing the filter cake, cm;

r₂the outer diameter of the core is cm without filter cake;

P_wrupture pressure, MPa;

μ₁the friction coefficient between the interface and the set cement is dimensionless;

μ₂the friction coefficient between the two interfaces and the rock core is dimensionless;

theta is the included angle between the two interfaces and the horizontal plane, and theta is more than 0 degree and less than 180 degrees.

Technical Field

The invention relates to a cementing quality evaluation device and method for a cementing two-interface in the field of oil and gas well exploration and development in the cementing process.

Background

For oil and gas well cementing and completion engineering, the cementing surface between a casing and a cement sheath is generally called a cementing interface, and the cementing surface between the cement sheath and a stratum is generally called a cementing interface. The cement sheath body and the first and second well cementation interfaces form a well cementation cement sheath sealing system. The quality of the well cementation and sealing system is directly related to the productivity and the service life of the oil and gas well and the development benefit of the oil field. If the interlayer packing capacity of the cement ring is reduced or even the interlayer packing effect is lost, formation fluid channeling and wellhead annulus pressure are induced, and normal oil and gas production is influenced. The main reason for causing the channeling is that the drilling fluid is lost to form a filter cake on the well wall in the drilling process, and the existence of the filter cake causes the well cementation cement paste to be not tightly cemented into a whole during well cementation, thereby providing a channel for the channeling of formation fluid and causing a series of well cementation problems.

The conventional method for evaluating the cementing quality of the two interfaces for indoor research has certain defects and shortcomings. Some scholars use a press machine to test the shear pressure (tregoring, warrior, CuiMaorong, and the like) required for the complete slippage of the rock core and the cement sheath in the presence of a filter cake, and a new method for evaluating the influence of the filter cake of the drilling fluid on the cementing quality of a well cementation second interface [ J ]. the natural gas industry, 2006,26(12):92-93), but the actual situation is that the slippage of the rock stratum and the cement sheath hardly occurs underground and the packing capacity of the second interface on formation fluid cannot be evaluated; some researchers consider the filter cake as a permeable substance, and use liquid to test seepage flow rate through a sample at one end of the core, so as to evaluate the cementing quality of the two interfaces (consider army, yankee, qin weng, oral. well cementation two-interface packer ability evaluation method research [ J ]. petroleum bulletin, 2008,29(3)), but the method does not consider that liquid can seep from the core, and also cannot reflect the cementing quality of the real well cementation two interfaces.

Disclosure of Invention

The invention aims to provide a cementing quality evaluation device for a well cementation two-interface, which has reliable principle and simple and convenient operation, can effectively avoid the seepage of fluid from a rock core, truly reflects the cementing quality of the well cementation two-interface and has wide market prospect.

The invention also aims to provide a method for evaluating the cementing quality of the two well cementation interfaces by utilizing the device, which forms a fluid channeling channel on the two interfaces by pressurizing the fluid to penetrate the two interfaces with filter cakes, and obtains the cementing coefficient of the two interfaces according to the fluid channeling pressure of the two interfaces so as to evaluate the cementing quality of the two interfaces.

In order to achieve the technical purpose, the invention adopts the following technical scheme.

The cementing quality evaluation device for the well cementation two-interface consists of a cylindrical kettle body, a rock core, a heating sleeve, a heat insulation sleeve, a fluid pressure pump, a pressure sensor and the like. The inner diameter of the kettle body from the top to the bottom is gradually reduced, the inner wall of the kettle body forms an inverted circular truncated cone shape, a rock core is arranged in the kettle body, the rock core is plastically packaged after a filter cake is formed on the surface of the rock core, and a cement sheath is arranged between the rock core and the inner wall of the kettle body. The top of the kettle body is provided with a detachable upper sealing cover, the upper sealing cover is provided with a liquid inlet, a pressure release valve and a pressure sensor which are communicated with the inside of the kettle body respectively, the liquid inlet is connected with a fluid pressure pump through a pipeline, and the pipeline is provided with a one-way valve communicated to the inside of the kettle body through the fluid pressure pump. The bottom of the kettle body is provided with a detachable lower sealing cover, the rock core is placed on the inner surface of the lower sealing cover, the lower sealing cover is provided with a liquid outlet communicated with the inside of the kettle body, the liquid outlet is arranged between the rock core and the inner wall of the kettle body, and the outer wall of the kettle body is provided with a heating sleeve.

Preferably, the upper sealing cover is of an inverted U shape, a first sealing ring is arranged between the inner side wall of the upper sealing cover and the outer wall of the top of the kettle body, and the inner side wall of the upper sealing cover is in threaded connection with the outer wall of the kettle body.

Preferably, the lower sealing cover is U-shaped, a second sealing ring is arranged between the inner side wall of the lower sealing cover and the outer wall of the bottom of the kettle body, and the inner side wall of the lower sealing cover is in threaded connection with the outer wall of the kettle body.

Preferably, the liquid outlet air outlets are at least two and are uniformly distributed between the rock core and the inner wall of the bottom of the kettle body.

Preferably, the included angle formed by the inner wall of the top of the kettle body and the outer wall of the top of the kettle body is 7-8 degrees.

The method for evaluating the cementing quality of the well cementation second interface by using the device sequentially comprises the following steps:

(1) placing the rock core in a filter cake pressing device to form a compact drilling fluid filter cake on the surface of the rock core;

(2) placing the rock core with the filter cake in a vacuum tank, and dripping resin into the rock core while vacuumizing to saturate the rock core with resin, wherein the resin can be coagulated together with cement slurry without affecting the structure of the filter cake;

(3) placing the core into a kettle body, adding well cementation cement slurry into an annular space between the core and the kettle body, and maintaining for a certain time under the experimental requirement condition to form a cement sheath between the core and the inner wall of the kettle body;

(4) a fluid pressurizing pump injects fluid into the kettle body through a one-way valve and a liquid inlet, when the pressure is raised to a certain value, the fluid penetrates through two interfaces where filter cakes exist, a fluid channeling channel is formed on the two interfaces, and the fluid is discharged through a liquid outlet and a gas outlet;

(5) recording the fracture pressure when the filter cake of the second interface is damaged to form a fluid channeling channel to obtain a cementation coefficient of the second interface, thereby evaluating the cementation quality of the second interface, wherein the calculation formula of the cementation coefficient of the second interface is as follows:

in the formula, gamma is a two-interface cementation coefficient and is dimensionless;

r₁is the outer diameter of the core containing the filter cake, cm;

r₂the outer diameter of the core is cm without filter cake;

P_wrupture pressure, MPa;

μ₁the friction coefficient between the interface and the set cement is dimensionless;

μ₂is the coefficient of friction between the two interfaces and the core,dimensionless;

theta is the included angle between the two interfaces and the horizontal plane, and theta is more than 0 degree and less than 180 degrees.

The fracture pressure is the fluid channeling pressure in the filter cake state, the two-interface cementation quality is in direct proportion to the two-interface cementation coefficient, namely the larger the two-interface cementation coefficient is, the better the two-interface cementation quality is, and conversely, the smaller the two-interface cementation coefficient is, the worse the two-interface cementation quality is.

Compared with the prior art, the invention has the beneficial effects that:

(1) the invention truly simulates the bottom hole environment during well cementation under the heating and pressurizing environment, and forms a fluid channeling channel at two interfaces through the fracture of a filter cake.

(2) The filter cake is used as a weak layer of the two interfaces, and the pressure value is brought into a mathematical model to be calculated as a basis for visually expressing the cementation condition of the two interfaces, so that the actual condition of the two interfaces is closer to the actual condition in a well.

(3) The inner diameter of the kettle body is gradually reduced from the top to the bottom, and the inner wall of the kettle body forms an inverted circular truncated cone shape, so that the cement stone can be prevented from integrally slipping and is consistent with the actual underground condition; the included angle formed by the inner wall of the top of the kettle body and the outer wall of the top of the kettle body is 7-8 degrees, so that the anti-falling effect is better.

(4) By forming the core with the filter cake and plastic package, the core after plastic package can avoid fluid seepage from the core, so that the test result is more accurate.

Drawings

FIG. 1 is a schematic structural diagram of a cementing quality evaluation device of a cementing two-interface.

Fig. 2 is a schematic structural diagram of the sealing cover on the device.

FIG. 3 is a diagram of the stress state of the two-interface bond.

Reference numbers in the figures:

1-kettle body, 2-upper sealing cover, 3-lower sealing cover, 4-core, 5-heating jacket, 6-liquid inlet, 7-liquid outlet, 8-heat preservation jacket, 9-pressure release valve, 10-one-way valve, 11-fluid pressure pump, 12-pressure sensor, 13-pressure recorder, 14-sealing ring III and 15-bolt.

Detailed Description

The present invention is further described below with reference to the accompanying drawings so as to facilitate understanding of the present invention by those skilled in the art. It is to be understood that the invention is not limited in scope to the specific embodiments, but is intended to cover various modifications within the spirit and scope of the invention as defined and defined by the appended claims, as would be apparent to one of ordinary skill in the art.

As shown in fig. 1-2.

The cementing quality evaluation device for the well cementation two-interface consists of a cylindrical kettle body 1, a rock core 4, a heating sleeve 5, a heat insulation sleeve 8, a fluid pressure pump 11, a pressure sensor 12 and a pressure recorder 13.

The inner diameter of the kettle body 1 from the top to the bottom is gradually reduced, the inner wall of the kettle body forms an inverted circular truncated cone shape, and the kettle body is provided with an upper sealing cover 2 and a lower sealing cover 3 which are detachable; the upper sealing cover 2 is provided with a liquid inlet 6, a pressure release valve 9 and a pressure sensor 12, the liquid inlet is connected with a fluid pressure pump 11 through a one-way valve 10 and a pipeline, and the pressure sensor is connected with a pressure recorder 13; the lower sealing cover 3 is provided with a liquid outlet 7; a rock core 4 is arranged in the kettle body, the rock core is placed on the inner surface of the lower sealing cover, a filter cake is arranged on the surface of the rock core, and a cement sheath is arranged in an annular space between the rock core and the kettle body; the kettle body is externally provided with a heating jacket 5 and a heat preservation jacket 8.

The inner wall of the top of the kettle body and the outer wall of the top of the kettle body form an included angle of 7-8 degrees.

And at least two liquid outlet air outlets 7 are arranged and are uniformly distributed between the rock core and the inner wall of the kettle body.

The heating device is characterized in that an electric heating wire is arranged in the heating sleeve 5 and connected with a heating control device, a heat preservation sleeve 8 is arranged on the outer surface of the heating sleeve 5, and the heat preservation sleeve 8 is made of glass wool or rock wool.

The upper sealing cover 2 is of an inverted U shape, a first sealing ring is arranged between the inner side wall of the upper sealing cover and the outer wall of the top of the kettle body 1, and the inner side wall of the upper sealing cover is in threaded connection with the outer wall of the kettle body; the lower sealing cover 3 is U-shaped, a sealing ring II is arranged between the inner side wall of the lower sealing cover and the outer wall of the bottom of the kettle body 1, and the inner side wall of the lower sealing cover is in threaded connection with the outer wall of the kettle body.

As shown in fig. 2, the upper sealing cover 2 is provided with a downward positioning protrusion, the top of the kettle body 1 is provided with a positioning groove matched with the positioning protrusion, a third sealing ring 14 is arranged in the positioning groove, and the upper sealing cover is sealed with the top end of the kettle body through a bolt 15.

The invention evaluates the cementation quality of the two interfaces through the cementation coefficient of the two interfaces, and the calculation formula of the cementation coefficient of the two interfaces is as follows:

in the formula, gamma is a two-interface cementation coefficient and is dimensionless;

r₁is the outer diameter of the core containing the filter cake, cm;

r₂the outer diameter of the core is cm without filter cake;

P_wrupture pressure, MPa;

μ₁the friction coefficient between the interface and the set cement is dimensionless;

μ₂the friction coefficient between the two interfaces and the rock core is dimensionless;

theta is the included angle between the two interfaces and the horizontal plane, and theta is more than 0 degree and less than 180 degrees.

The derivation of this equation is as follows:

taking the cement sheath as a research object, and taking the two-interface cementing interface for stress analysis, thereby listing a balance equation of the two-interface cementing stress interface (see figure 3).

As can be seen from FIG. 3, the two interfaces have two stress directions, wherein the downward stress interface, i.e. the stress interface equation in the pressurizing direction, is as follows:

F_w＝P_w×A_c (2)

the upward force, i.e. the resistance in the pressurizing direction, is divided into the following parts:

the vertical filter cake reaction force interface equation is:

F＝(P_w-P_wsinθ)×A_c (3)

the internal stress interface equation of the cementing action is as follows:

F_γ＝γC₁ (4)

the interfacial equation of the cementing friction force with the cement sheath is as follows:

F₁＝(P_w-P_wsinθ)×C₁μ₁ (5)

the equation of the cementing friction force section of the rock core is as follows:

F₂＝P_wC₂μ₂ (6)

at the instant of filter cake rupture, the forces on both sides are balanced, and the equations (2), (3), (4), (5) and (6) can be derived:

(P_w-P_wsinθ)A_c-γC₁+(P_w-P_wsinθ)C₁μ₁+P_wC₂μ₂＝P_wA_c (7)

expanding the formula (7) to obtain:

in the formula: a. the_cIs a cement sheath and filter cake cementation stress section m²；C₁The length of the lateral arc of the cement ring is m; c₂The arc length of the side surface of the rock core is m; n is central angle degree; r is₁The position contains the outer diameter of the filter cake, m; r is₂Is the inner diameter of the filter cake free, m; gamma is a two-interface cementation coefficient and is dimensionless; p is a radical of_wRupture pressure, MPa; mu.s₁The friction coefficient between the interface and the set cement is dimensionless; mu.s₂The friction coefficient between the two interfaces and the rock core is dimensionless; theta is the included angle between the two interfaces and the horizontal plane, and theta is more than 0 degree and less than 180 degrees.

The formula (8) is simplified to obtain:

the relationship between the two interfacial bond coefficients and the fracture pressure is thus obtained: